Financial support is being sought for the Thirteenth Meeting of the International Society of Sexually Transmitted Diseases Research (ISSTDR-99). The centerpiece of the meeting will be presentation of original scientific research selected from abstracts submitted for competitive consideration. Invited speakers will give plenary state-of- the-art lectures, and invited program chairpersons will give brief presentations to introduce each scientific session. A variety of special symposia, primarily organized around several invited presentations, will explore specific scientific domains in detail. The meeting is organized into four "tracks": Track A, Basic Science; Track B, Clinical Science; Track C, Epidemiology; and Track D, Social Sciences, Behavior and Prevention. HIV/AIDS is dealt with as follows: biologic interactions between HIV and sexually transmitted pathogens are dealt with in Track A. Assessment of the influence of the interaction between traditional STD's and HIV and the potential benefits of preventing STD's to reduce HIV infection incidence are included in Tracks B and C. The issues dealt with in Track D are generic and are of major importance in understanding the transmission of all STD's, including HIV. The emphasis will be on prevention of STD's in the broadest sense i.e., primary, secondary and tertiary prevention and in understanding the determinants of sexual behavior and ways to effect behavioral changes to reduce risk.